Patent GB-541053-A (GB)
Title: An improved four-stroke internal combustion engine using crankcase compression
IPC: F02B75/24
Filed: 1940-05-28
Abstract: 541,053. Four-stroke engines ; cylinders ; valves; lubricating. GWILLIAM, V. C. E. MARTEN-. May 28, 1940, Nos. 9335/40 and 6760/41. [Classes 7 (ii) and 7 (vi)] [Also in Groups XXIV and XXXIII] A four-stroke engine in which the charge is compressed in the crankcase comprises a pair of horizontally-opposed cylinders or cylinder banks mounted on or contiguous with a common crankcase, a crankshaft fitted with crank discs, a rotary or disc induction valve leading from a carburetter or the atmosphere to the crankcase interior, and an inertia-operated inlet valve or valves mounted in each piston head to transfer the charge to the cylinders. In one form, Figs. 2 and 5, the charge enters the crankcase by way of an inlet 1, 23 and sectorshaped ports 7 in a flange of the bearing bush 4 and in the crank disc 6. Each piston head 11 is fitted with a seating 10 for an inlet valve 9 the stem of which moves in a guide 13 supported by radial arms 12, which may be inclined to give the charge a whirling motion. Radial slots 16 in the valve stem are engaged by keys on plungers 14 actuated by springs 18, and the contacting parts of the slots and keys may be curved or inclined to control the movement of the valve, which opens by inertia on the inlet stroke of the piston. One piston performs its inlet stroke while the opposed piston performs a power stroke, so that the charge from the crankcase is admitted alternately to one and the other of the two cylinders. The ellipsoidal combustion chambers are partly separated from the cylinders by annular flanges 20. Exhaust valves 35 in the cylinder heads are actuated through levers and tappet rods 32 from cams on a shaft 21 driven through timing gears which serve to pump lubricating oil to an orifice 22 in the main bearing bush 4, Fig. 5, from which the oil passes through a spiral groove in the bush and radial grooves in the member 5 into the incoming charge in the inlet port 23. Oil also passes through the hollow cam shaft 21 and is flung out through radial holes 28 in the cam face. An oil seal for the crankshaft at the end remote from the inlet port comprises a resilient diaphragm secured in gastight manner at its outer edge to the crankcase and bearing at its inner edge against a ring of graphite-impreg  nated bronze on the crankshaft at the side of the crank disc. The shallow chamber formed by the diaphragm is in communication with the pressure side of the timing-gear pump. In a modification, Figs. 6 and 13, each of a pair of banks of eight cylinders is cast in one with a longitudinal half of the crankcase aggregate, which is divided by walls 38 into separate crankcases. The induction valves 40 are rings having toothed edges engaging the crank discs. The air enters gaps 44 between the crank cases and is controlled by rectangular throttle valves 45 in intake mouths; these valves may be actuated by an altitude aneroid on one side of the engine and an over-riding manual control on the other. The compression in each crankcase may be indicated by a spring- loaded plunger operating a variable resistance of the compression-stack type, arranged to move one of a series of vertical rods which indicate whether the compression is maintained in all the crank cases. The exhaust-cam shaft 49, in two halves in line, is driven through gears 50-52 forming the main oil pump, the lubricating-arrangements for the valve gear being similar to those in Figs. 2 and 5. Lubrication of the cylinder walls and gudgeons is from the cam-shaft bearings 58 through pipes 59, non-return valves 60 and holes in the piston bosses. Helical grooves 61 in each main bearing are fed by ducts 56 from cam-shaft bearings 57 and lead to ducts 62, 63 conveying any excess oil to the oil cooler. The crankshaft comprises a one-piece forging on each side of each intermediate bearing, the forging comprising crank-arms, balance weights and the journals 64, and each crankpin is splined or attached to a crank-web 65, locking being effected by nuts 66 engaged by worms 67. Crank-discs in the form of split hollow or solid drums 68 of magnesium or other light alloy are spigoted and bolted to the crankarms. The open sides of the connecting-rods may also be filled with light alloy 78. The valves 70 are each mounted in the piston by means of a detachable hollow casting of aluminium-bronze or other alloy, which is secured by studs and nuts and may be partly filled with sodium. The casting may be enlarged to form the ring-carrying portion of the piston. In a suggested layout for aeroplanes, Figs. 15 to 17 (not shown), each air-intake is connected to slotted openings in the underside of the wing and the exhaust is ejected below the wing through stub pipes. A mathematical analysis is given of the action of the inertia-operated inlet valves and of the engine cycle.